| Hastelloy C-276 | PREN ~45; Unparalleled resistance to highly reducing environments, extreme sour gas (H₂S), and Sulfide Stress Cracking (SSC). | North Field Upstream, Ras Laffan LNG Flanges |
| Hastelloy C-22 | PREN ~46; Higher chromium content provides vastly superior defense against oxidizing acids, wet chlorine, and mixed chemical streams. | Mesaieed Petrochemical (QAFCO), RO Desalination |
| Super Duplex | Effective for bulk piping but highly vulnerable to localized crevice corrosion during stagnant, aerated plant shutdowns. | Low-risk seawater intakes (Limited high-stress bolting) |
| Alloy 20 / Inconel | Specified per Shell DEP guidelines where precise temperature or specific acidic resistance is demanded. | Specialized Downstream Refining |